Arsenic's toxicity comes from the affinity of arsenic(III) oxides for thiols. Arsenic apparently affects numerous intracellular sig-nal transduction pathways and causes many alterations in cellular func-tion. Arsenic (As) contamination affects hundreds of millions of people globally. the toxicity and potential carcinogenicity of long-term exposure to envi-ronmental arsenic. Inorganic arsenic is generally more toxic than organic arsenic. There is equally varia-t io nh er ad x f m yl b w sp c and between human populations (Vahter, 1994, 1999 and 2000; Hughes, 2002). In addition to reviewing the literature on As contamination and toxicity, we prov … Thiols, in the form of cysteine residues and cofactors such as lipoic acid and coenzyme A, are situated at the active sites of many important enzymes. These actions of arsenic may result in the induction of apoptosis, the The chapter is divided into two major sections-cancer and noncancer effects. Although the number of patients with chronic As exposure is large, the symptoms and long-term clinical courses of the patients remain unclear. Biological mechanism. Toxicity by Form: Arsenic toxicity may vary by form. Arsenic Toxicity and Molecula r Mechanism of Arsenic Tolerance in Di fferent Members… 166 endodermis and e xodermis, unlike OsLsi1, which are localized on the distal side. Arsenolysis, another mechanism of toxicity, results when arsenic anions disrupt oxidative phosphorylation by replacing stable phosphoryl with less stable compounds. Observing how the genome changes in response to arsenic exposure may help us learn more about the mechanism of arsenic toxicity.” Pierce hypothesized that arsenic may act on telomeres to cause toxicity in cells. The type of organic arsenic found in certain seafood (arsenobetaine and arsenocholine) appears to have low toxicity. Another mechanism of arsenic toxicity is the methylation of inorganic arsenic which occurs in most though not all mammalian species. Arsenic is a known human carcinogen, but the specific mechanisms by which it causes cancer are less well understood. Arsenic is considered to be a heavy metal, and arsenic toxicity shares some features with poisonings by other heavy metals. Arsenic is a natural semi-metallic chemical that is found all over the world in groundwater. The cell then self-destructs in an attempt to restore lost energy. “Telomeres are one of the features of the genome that change over time,” said Pierce. Unstable arsenic compounds irreversibly decompose, resulting in loss of high-energy phosphate bonds. Arsenic poisoning, or arsenicosis, happens when a person takes in dangerous levels of arsenic. Although numerous mechanisms for arsenic toxicity have been proposed, its ability to induce imbalances between antioxidant and pro-oxidant levels resulting in cellular damage through ROS generation is the currently accepted mechanism. Historically, arsenic has been used as a medicinal agent, a pigment, a pesticide, and an agent with intent to harm (use with criminal intent). signs of arsenic poisoning may be reduced if the quality of drinking water were improved. Inorganic arsenic compounds (such as those found in water) are highly toxic while organic arsenic compounds (such as those found in seafood) are less harmful to health. Acute effects. Arsenic can also occur in an organic form. Arsenic disrupts ATP production through several mechanisms. In this chapter, the subcommittee summarizes what is known about the mechanisms of toxicity for arsenic. “They shorten as we age. Arsenic free ... is free from arsenic due to modification inside body or some barrier action of unknown mechanism. 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